Firstly, we will understand about the term solutions. Afterwards, we will discuss the ways of expressing concentration of solutions.

Expressing the concentration of the solutions

A solution is a homogeneous mixture of two or more chemically non reacting solute and solvent components. Solute is the component which is present in lesser amount in the solution. Solvent is the component present in the excess in the solution. For example in sugar or salt aqueous solution, the solute component is sugar/salt and H2O is the solvent.

Let’s discuss the various methods to express the concentration of the solution

1. Strength of Solutions

The strength of the solution is defined as the amount of the solute in grams dissolved per litre of the solution

Strength of solutions (g/l) = mass of solute in (g) / volume of the solution (litres)

2. Percentage of solutions

(A) Percentage by mass (m/m)

Mass of solute present in grams dissolved present in 100g of solution.

(B) Percentage by mass per unit volume ( m/v )

Mass of the solute present in grams dissolved in 100 ml of the solution

(C) Percentage by volume ( v/v )

Volume of solute in ml present in 100 ml of solution.

3. Molarity of solution

Number of the moles of solute dissolved per litre of the solution is called as the molarity of the solution. For example, if a solution of H2SO4 contains 4.9 g of it dissolved in 500 ml of solution will have the molarity :

Molarity = 4.9g/98g/mol*1000/500ml

H2SO4 Molarity = 0.1mol/L

4. Normality of solution

Number of gram equivalents of the solute dissolved per litre of the given sol.

Normality = Number of gram equivalents / Volume of the solution (L)

Gram equivalents = mass of solute (g) / Equivalent mass

Equivalent mass of acid = Molar mass of acid / Basicity of acid

The Equivalent mass of base = Molar mass of base / Acidity of base

Equivalent mass of salt = Molar mass of the salt / total positive valency of metal atom

5. Molarity equation

M1V1 = M2V2 ( For 2 different solutions having different molarities and different volumes )

6. Normality equation

N1V1 = N2V2 ( For 2 different solutions having different molarities and different volumes )

7. Mole fraction

The mole fraction is defined as the ratio of moles of any one component that is solute and solvent to the total number of moles of solute and solvent present in the solution.

Mole fraction = Moles of solute or solvent / total number of moles of solute and solvent present in solution.

You can watch the video on numerical on concentration of solution.

Here is the video on concentration of solution to explain the content and try some of the numericals from sol.

You can also read the articles on the structure and bonding of some simple molecules like H2O

Stay in tune for more posts to come !

Thank you !